Spark plug



Nov. 8, 1949 J. J. FERNANDEZ 2,487,535

SPARK PLUG Filed June 15, 1945 Elmo/WM Jazz; Jdzvz'sjrmazdag mouth providing Patented Nov. 8, 1949 UNITED STATES PATENT OFFICE 2,487,535 SPAR PLUG John J. Fernandez, Baltimore, Md.

1945; Serial No. 599,191

Application June 13,

19 Claims. (CI. 1.23-4.69.)

The present invention relates to improvements in spark plugs employed in igniting the chargesv in internal combustion engines.

All spark plugs now commonly employed have a relatively limited heat range. When, therefore, the operating conditions of the vehicle are changed, it often happens that the previous set of spark plugs run too hot or too cold, and the performance of the engine is seriously affected. When a plug runs too hot the insulator may become heavily coated with oxides, and the firing points may wear rapidly, and in extreme conditions preignition may take place. When the plug runs too cool soot and carbon may deposit on the insulators causing missing. As an example, a truck or bus, when changed from city to highway traffic, may experience the difficulties described above as due to the plugs running too hot. In order to meet these conditions spark plug manufacturers provide a line of plugs in each diameter size to meet the varying running conditions.

The present invention aims to provide a spark which has a relatively large heat range, thereby substantially eliminating the need of changing plugs with varying conditionsof operation of the vehicle.

. A further object of the present invention is to provide a spark plug, which by reason of its construction and design is self cleaning thereby substantially reducing the possibility of the plug fouling and missing.

To obtain. the above ends the. plug of the present invention is provided with a. constricted a Venturi effect at the mouth the plug. The increased speed of the vapors and gases at the mouth of the chamber serves to minimize the deposition of materials on or in the vicinity of the elec-. trodes. The constricted passage and the consequent increased speed of the gases also serve to increase the rate at which the heat is carried away from the sparking zone and from the electrodes.

Further to assist in the performance of the spark plug one of the electrodes is shaped in the form of an annular or curved fork as shown so that it serves to constrict the mouth of the of the chamber in plug and additionally also aids in conducting excessive heat away.

Further objects and advantages of the invention will be understood by persons skilled in the art from the accompanying drawing and the following specification; these are illustrative of one embodiment of the invention and that variations thereof falling within the scope of the appended claims will be apparent to persons skilled in the art.

In the drawings;

it being understood that Fig. 1 is an enlarged elevation, partly in section of a plug embodying the invention; and

Fig. 2 is a bottom view of the plug.

In the drawings, the invention is shown embodied in a spark plug having the conventional spark plug central electrode I0 supported by a ceramic insulator H. The plug barrel l2- and nut l3 grip the insulator ll.

In the present invention, the shape of the mouth or open end of the chamber I4 is constricted. For this purpose the mouth end of the barrel provided with an annular inwardly directed lip l5 which forms a Venturi throat or mouth as shown. The inner face of the barrel 12 forming the chamber I4 will be seen to have a cylindrical portion l6 and an inwardly convex portion ll, the convex portion extending considerably into the interior and toward the central electrode ID.

The electrode I8 is carried by the barrel mouth portion 45 and consists of the stem l9 and the split ring or fork 20. Each semicircle of the split ring 20 will be seen as tapering off from the stem I9. toward the free ends of the semicircles.

The spark plug embodying the present invention when compared in operation with the conventional spark plug of the same dimensions is found to have a greatly extended heat range without preignition, without fouling and with a general improvement in the operation of the engine. Consequently the same plug can be used either in a high compression or low compression engine, and the same plug can be used in the engine with gasoline of the various grades,

The Venturi effect which causes high velocities of gases adjacent the electrodes aids in prevent- 1 ing overheating of the electrodes, when the en-.

greatest when gine is operating under heavy load. During idling or light load the Venturi effect is comparatively low, or too low to cause any excessive cooling of the electrodes' It at the same time tends to carry away any solids or liquids that may form in the vicinity of the electro-des and which otherwise would depos't on the electrodes and tend to foul the plug.

The fork electrode 20 also aids during high load to prevent overheating of the plug by carrying the heat away by conduction. Thus, the venturi causes the gases to carry the heat away by conduction and convection and the fork elec-.- trode carries it away by conduction. The total effect is that the rate of cooling of the plug is the engine runs hottest.

The enlarged showing in the drawings indicates the preferred proportioning of the dimensions at the mouth of the plug, although the dimensions and proportions may be varied over a,v

Generall he area i he annula the le trode an hould be substan wide range, pa-cs outside tially greater than the annular space inside the ing two arcuate arms annularly spaced from said electrode 20. As shown the relationship is lip and from the end of the central electrode, said roughly two to one, but this may be varied over arms tapering oil in cross-section from their ata considerable range. The tapering of the fork tachment points to their free ends, the area of fork and this also prevents burning ofi or conand the lip being substantially greater than the sumption of the tips of the fork which at the annular space between the electrodes. same time provide for high heat conduction to 6.. A spark plug having an insulating core, a the barrel of the P d to the cylinder block. central electrode carried by said core, a metal The split fork also ermits adjustment of the air shell for said core forming an open mouthed gap when desired. chamber with said core, the shell having an 1ns s wn t p n 5 is in r l with and te ral annular inwardly directed lip at its mouth, of the s m m ri l s he barrel I2 of the p u a second electrode attached to said lip and hav- It will be understood, however, that if desired ing t arcuate arms annularly spaced from said the annular end portion 2| of the barrel (as lip and from the end or the central electrode, said d c d y the d t d lines) ay be mad f a arms tapering off in cross-section from their atmore highly heat conductive material such as tachment points to their free ends, the area of brass or the like. the annular space between the second electrode W I Claim as 116W and desire t0 Secure by and the lip being approximately twice as great as Letters Patent of the United States is: the area of the annular space between the elec- 1. A spark plug having an insulating core, a t

central electrode carried by said core, a metal 7 A spark plug havin a insulating core, a

shell for said core, an annular lip on the interior central electrode carried by Said core, a t l face of the Shell at Open and providing shell for said core, the shell having an annular lip shell, the central electrode ending in the plane mg two arcuate arm mouth into two annular areas, with the outer annular area substantially greater than the inner annular area.

2. The spark plug of claim 1 in which the annular second electrode is enlarged in the zone of attachment to the shell and is split at the diacurved outline, and a second annular electrode carried by said lip, disposed within the plane of the lip and circumferentially spaced from said lip, the area of the annular space between the second electrode and lip being substantially greater than the area of the annular space between the central and second electrodes.

4. A spark plug having an insulating core, a

and the lip being substantially greater than the annular space between the electrodes.

chamber with said core, said shell having an an- 10 A spark plug having an insulating core a the second electrode being approximately twice the area of the annular space between the elect e chamber with said core, the shell having an inrod 8 JOHN FERNANDEZ central electrode carried by said core, a metal a second electrode attached to said lip and hav- 5 (References on following page) Number REFERENCES CITED 1,958,580 The following references are of record in the 2,060,219 file of this patent: 2,171,164 UNITED STA'IES PATENTS 2350331 Number Name Date Re. 15,303 Blodgett et a1 Mar. 14, 1922 Number 1,281,322 Ferraris Oct. 15, 1918 538110 1,339,463 Lockewitz May 11, 1920 w 1,942,242 Fitzgerald Jan. 2, 1934 Name Date Kasarjian May 15, 1934 Kasarjian Nov. 10, 1936 Rabezzana Aug. 29, 1939 Dobrosavljevitch June 6, 1944 FOREIGN PATENTS Country Date France June 3, 1922 

